Single wythe masonry walls are constructed using concrete masonry units (CMUs). CMUs are sometimes referred to as cinder blocks. A CMU consists of a hollow rectangular building block typically having a central web providing two vertical cores or cavities. In singly wythe masonry wall construction a foundation is formed, typically of concrete. The wall is formed by laying the CMUs in alternating fashion in multiple courses depending on the height of the wall. Owing to the construction, the vertical cores of CMUs are aligned to provide a continuous channel from the top of the wall down to the foundation. Mortar is used in joints to join the CMUs.
Cracks in the CMUs can allow water to enter the cores. Moisture can also condense in the cores under changing temperatures. Either way, water may collect in the cores in the CMUs.
The presence of moisture in the cores is undesirable for a number of reasons. First, the trapped moisture can degrade the structure. Second, the presence of water under freezing temperatures may also cause cracks in the wall when water expands as it freezes. Trapped water in the cores in the CMUs may cause the CMUs to become discolored, and may even migrate into the dwelling.
To overcome the problems associated with water trapped within the CMU cores, weep holes are commonly included along the base of the outer side of the CMUs in the lowermost course. The weep holes allow water to pass from the core to drain outside the wall structure. A flashing disposed in the core directs the collected water toward the weep holes.
During construction of a single wythe masonry wall, excess mortar and other debris can and does fall into the cores. When the CMUs are stacked during the erection of the wall, for example, mortar droppings are squeezed into cores within the CMUs. The excess mortar, as well as other debris, such as insulation, drops to the base of the core, and can block weep holes.
One known solution is to construct a CMU drainage course consisting of two wythes separated by a cavity sized to accommodate through wall flashing and blocks of water permeable material. This solution uses different style concrete blocks in the drainage course.
Another known solution, shown in U.S. Pat. No. 6,202,366, uses a collection pan under each CMU core of a selected course to collect water in the core. A weep channel on the pan drains the water to the exterior of the wall. This solution requires a collection pan for each core. Also, each pan must be aligned prior to applying mortar so that once a subsequent course is laid each pan is properly aligned with the CMU.
The present invention is directed to solving one or more of the problems discussed above, in a novel and simple manner.